Meanwhile, the company has been dealing with a separate but equally massive problem: disastrous global sales results. There are signs of improvement, but the share price is still less than half their value back in 2010.

Cohen would give favoured executives this tiepin, with a mysterious motto, "YCDBSOYA."

Cohen died in 1979.

But his company's market share eventually surpassed Sainsbury's, becoming nearly twice as big as it nearest rival.

Kantar Worldpanel

By the early 2000s, Tesco was on track for global domination.

Customers shop at a newly opened Tesco supermarket in Beijing January 26, 2007.REUTERS/Jason Lee

Tesco opened hundreds of stores in China. But its largest presence outside the UK is Homeplus, its Korean arm, with over 400 stores. It also operates in India, Malaysia, and across the EU, often under different banners.

The expansion in the early 2000s put it next to France's Carrefour for the title of the world's second biggest retailer (Walmart is first).

But sales did not keep pace with the store's ambitious expansion plans.

A customer service representative stands in the home ware department at a Tesco Extra supermarket.REUTERS/Suzanne Plunkett

In real terms, Tesco’s sales per square foot are currently at their lowest levels since 2005. After accounting for inflation, it's even worse.

The 2008 financial recession triggered a global retreat.

A fishmonger fillets a mackerel at a Tesco Extra supermarket.REUTERS/Suzanne Plunkett

Tesco had accumulated a huge amount of floor space and land, with the anticipation of expansion that never truly filled it.

While other companies began cutting prices to cater for newly poor shoppers, Tesco was slower to respond.

Even China didn't work out.

A balloon vendor waits for customers outside a Tesco supermarket in Shanghai.REUTERS/China Daily

Tesco began talking to China Resources Enterprise, a massive domestic retailer, about a potential partnership. In May 2014, it was announced that the Tesco's Chinese arm would merge with CRE, but that Tesco would only take a 20% stake in the firm.

In 2014, Tesco announced that £250 million in profits had simply disappeared.

REUTERS/ David Moir

Accountancy giant Deloitte was brought in to investigate. The retailer had warned months earlier that the way it registered commercial income was "at risk of manipulation" by auditors.

It also became apparent in the days after the announcement that Laurie McIlwee, Tesco's finance director, was not actually at work. McIlwee had already handed in his notice and had been effectively absent during the search for a replacement.

The fallout was ugly for management.

Richard Broadbent.Richard Broadbent

Tesco suspended four executives in the immediate aftermath of the profit fiasco, and a further three this October.

Lewis and new CFO Andy Stewart have been at the head of attempts to reform the company.

Despite a period of massive underperformance, Tesco has been catching up with the industry in terms of sales growth. It's now no longer losing significant market share, according to HSBC analysts.

HSBC

Discount chains Aldi and Lidl are still gaining, but the effect of competition is becoming slightly more muted compared to a year ago. Sales growth at both firms seems to be slowing, as is market share growth.

HSBC

HSBC maintains that, in the long-term, Tesco is better-placed to perform than the other major supermarkets due to its sheer size.

REUTERS/Stefan Wermuth

Tesco benefits from buying power, fixed costs (costs for things like advertising are more expensive for smaller companies if they want to match Tesco), and lower distributing costs due to the number of stores and employees.